The paper analyses the structural and technological determinants of the diffusion of international data network as a major technological and organizational innovation in a sample of 40 U.S. and European multinational firms in the period 1963-1980. According to the results faster adopters appeared to be large U.S. firms, exposed to worldwide competition, with inhouse telecommunication skills. Smaller European firms adopted the technology later, often pushed by the provision of ad hoc technical solutions by service and hardware marketing firms. Smaller latecomers with centralized management structures were, however, quicker in the diffusion process. Both in the interfirm and intrafirm diffusion ‘implicit knowledge’ was a more effective factor than R-D intensity.